1. Field of the Invention
The invention relates to methods and apparatus for placement and removal of pistons in cylinders and more particularly relates to an assembly and method for insertion and withdrawal of the piston component of a disc brake assembly.
2. Brief Description of the Prior Art
Prior hereto, the most commonly employed method of withdrawing the piston component of the conventional disc brake assembly has comprised disassembly of the caliper halves followed by introduction of compressed air into the brake line. Under the pressure of compressed air the pistons are generally projected with great acceleration out of their cylinders. On occasion even highly compressed air will not move a frozen piston out of the cylinder and it must be levered out with a chisel or like tool; see Basic Auto Repair Manual, 7th Revised Edition (1975), Edited by S. Murray, Peterson Pub. Co., Los Angeles, Calif., (Library of Congress Card No. 75-18057), Page 278. In either event there is a likelihood of damage to the piston and/or the cylinder during the withdrawal procedure. The piston as a projectile powered by compressed air is subject to damage as it strikes some object (usually the brake housing) and may even be a safety hazard to the operator. Rotation and levering of the piston in the cylinder likewise may damage the piston and/or the cylinder walls.
Also prior to my invention, special wrenches have been provided for gripping the piston component of disc brake assemblies. However, like the employment of a chisel these wrenches operate on the principle of rotating and levering the piston out of its cylinder, thereby potentially damaging the piston and/or cylinder. Prior to my invention, no convenient tools have been available for the manual insertion of pistons into the cylinder of a disc brake assembly. The most common practice heretofore has been to hammer the piston in place; see Basic Auto Repair, supra. This practice is undesirable since it may damage or weaken the piston.
By the method and assembly of my invention, the piston component of a disc brake assembly may be inserted or withdrawn with little potential for damage to the piston or its cylinder and without hazard to the operator. The assembly permits a straight, in-line withdrawal of the piston, reducing the likelihood of damage.